The invention relates generally to automatic riveting machines, and more specifically to an accessory for such machines which permits double flush riveting.
Conventional automatic riveting machines, such as those disclosed by F. A. Boyle in U.S. Pat. No. 2,598,106, and by J. J. White, et al in U.S. Pat. No. 3,030,695, are capable of rapidly installing and squeezing a variety of rivet shapes and types. However, they are generally incapable of countersinking a rivet hole on both sides of a sheet assembly and forming flush rivet heads on both sides. Such double flush riveting is highly desirable in a number of applications, such as in the seal contacting area of airplane doors and other assemblies where, for functional or aesthetic purposes, both exposed surfaces of the laminated assembly must be smooth.
In most automatic riveting machines, the sheets are clamped in place, a drill and countersink enter from above to form the rivet receiving hole, a lower anvil is positioned just below the rivet receiving hole, a rivet is installed and the rivet is squeezed between the lower anvil and an opposed upper anvil. In many operations the rivet has a preformed head of the desired shape, round head, brazier head, or flat head for example, and the rivet is inserted from the top side, thereafter the shank is headed on the lower side by squeezing to form a button-like lower head. In other operations a rivet slug is utilized and both the upper and lower heads are formed simultaneously by squeezing.